Process for preparing functional ceramics

ABSTRACT

According to the present invention, ceramics which are prepared by calcining a composition comprising raw ceramic materials and a microorganism and/or culture fluid thereof, wherein the microorganisms is capable of producing an antioxidation material. The ceramic of the present invention possesses a variety of activities of, for instance, improving the soil, decomposing sewage or sludge, and deodorizing an unpleasant odor.

This is a divisional of application Ser. No. 08/263,461 filed on Jun.22, 1994 now U.S. Pat. No. 5,521,131.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a functional ceramic having a widevariety of biological activities and a process for preparing the same.

2. Related Art

Ceramics possessing biological activities are known in the art.

For instance, functional ceramics provided with activities bycontrolling the internal physical structure, by calcining with materialshaving catalytic functions, or by adsorbing microbes or catalysts intothe pores of porous ceramics have been proposed.

However, most of the conventional functional ceramics, in general, havea single activity to be aimed. Further, the activity is sometimesinsufficient and may be lost with the passage of time. Particularly, theceramics provided with the activity by adsorbing microorganisms orcatalysis, further improvements are desired in some points. Forinstance, in the ceramics the density of microorganisms may vary withthe lapse of time. Moreover, the activity of ceramics may not be stable,unless environmental conditions, such as pH or temperature aremaintained constant.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to provide afunctional ceramic which possess a wide variety of activities and arestable and used for a long period of time.

According to the present invention, there provides a ceramic obtainableby calcining a composition comprising raw ceramic materials and amicroorganism and/or culture fluid thereof, wherein the microorganism iscapable of producing an antioxidation material.

According to the present invention, there also provides a process forpreparing a ceramic, comprising calcining a ceramic material with amicroorganism and/or culture fluid thereof, wherein the microorganism iscapable of producing an antioxidation material.

DETAILED DESCRIPTION OF THE INVENTION

Ceramic

The functional ceramic according to the present invention are obtainableby calcining composition raw ceramic materials and a specificmicroorganism and/or a culture thereof.

The microorganism employed in the present invention is capable ofproducing antioxidation material. The term "antioxidation material"herein means a material suppressing the oxidation of iron or a materialdecomposing or resolving an active oxygen. The antioxidation materialincludes, for examples, a variety of organic acids, amino acids andproteins.

Preferable specific examples of the microorganisms include:

the microorganisms belonging to actinomycetes include those belonging togenera Streptomyces, Streptoverticillium, Nocardia, Micromonospora andRhodococcus. Specific examples of actinomycetes include Streptomycesalbus (e.g. ATCC 3004), Streptoverticillium baldaccii (e.g . ATCC23654), Nocardia asteroides (e.g. ATCC 19247), Micromonospora chalcea(e.g. ATCC 12452) and Rhodococcus rhodochrous (e.g. ATCC 1380);

the microorganisms belonging to photosynthetic bacteria include thosebelonging to genera Rhodopseudomonas, Rhodospirillum, Chromatium andChlorobium. Specific examples of photosynthetic bacteria includeRhodopseudomonas sphaeroides (e.g. IFO 12203), Rhodospirillum rubrum(e.g. IFO 3986), Chromatium okenii and Chlorobium limicola;

the microorganisms belonging to lactic acid bacteria include thosebelonging to genera Lactobacillus, Propionibacterium, Pediococcus andStreptococcus. Specific examples of lactic acid include Lactobacillusbulgaricus (e.g. ATCC 11842), Propionibacterium freudenreichii (e.g. IFO12391), Pediococcus halophilus (e.g. IFO 12172), Streptococcus lactis(e.g. IFO 12007) and Streptococcus faecalis (e.g. IFO 12391);

the microorganisms belonging to mold fungi include those belonging togenera Aspergillus and Mucor. Specific examples of mold fungi includeAspergillus japonicus. (e.g. IFO 4060), Aspergillus oryzae (e.g. IFO4075) and Mucor hiemalis (e.g. IFO 5303); and

the microorganisms belonging to yeast include those belonging to generaSaccharomyces and Candida. Specific examples of yeast includeSaccharomyces cerevisiae (e.g. IFO 0304), Saccharomyces lactis (e.g. IFO0433) and Candida utilis. (e.g. IFO 0396).

According to the preferred embodiment of the present invention, a pluralof the microorganisms are employed. The microorganisms are preferablyselected from each of five groups of actinomycetes, phototrophicbacteria, lactic acid bacteria, mold fungi and yeast.

These microorganisms may be cultured under the conventional culturecondition of microorganisms.

The microorganisms and/or culture products thereof (the term "culturefluid" will mean hereinafter the microorganism and/or culture productsthereof) are added to raw ceramic materials, which are then calcined togive ceramic.

The raw ceramic materials herein means materials which can be calcinedto produce ceramic and includes those usually used in the production ofceramics. Specific examples of the raw ceramic materials include clay,zeolite, bakuhan-seki and the other materials of porcelains such askaolin, gainome-clay, kibushi-clay, pottery stone, feldspar. Theseceramic materials may be used alone or as a mixture of the two or more.In view of the physical properties, such as strength, of ceramic to befinally obtained, the raw ceramic materials are preferably those ofwhich the components are controlled.

Preferable specific examples of the clay include Akatsu-gaimome-clay(Aichi, Japan, Silicate: 50.14%, Titanium oxide: 0.50%, Alumina: 34.70%,Iron oxide:1.36%, Lime: 0.24%, Magnesia: 0.10%, Potassium oxide: 0.56%,Sodium oxide: 0.30%), Tokikuchi-gaimome-clay (Gifu, Japan, Silicate:47.51%, Titanium oxide: 0.46%, Alumina: 36.60%, Iron oxide:1.24%, Lime:0.22%, Magnesia: 0.21%, Potassium oxide: 0.60%, Sodium oxide: 0.04%),Shimagahara-gaimome-clay (Mie, Japan, Silicate: 48.14%, Titanium oxide:1.03%, Alumina: 35.01%, Iron oxide:1.17%, Lime: 0.54%, Magnesia: 0.28%,Potassium oxide: 0.44%, Sodium oxide: 0.40%), Motoyama-kibushi-clay(Aichi, Japan, Silicate: 45.48%, Titanium oxide: 0.62%, Alumina: 32.15%,Iron oxide: 0.74%, Lime: 0.29%, Magnesia: 0.24%, Potassium oxide: 0.54%,Sodium oxide: 0.19%), Hara-kibushi-clay (Gifu, Japan, Silicate: 51.88%,Alumina: 33.07%, Iron oxide: 1.83%, Lime: 0.42%, Magnesia: 0.25%,Potassium oxide: 0.92%, Sodium oxide: 0.17%), andShimagahara-kibushi-clay (Mie, Japan, Silicate: 49.78%, Titanium oxide:0.90%, Alumina: 29.74%, Iron oxide: 2.07%, Lime: 0.24%, Magnesia: 0.03%,Potassium oxide: 0.23%, Sodium oxide: 0.38%, Water: 15.76%).

The ceramic materials are preferably dried beforehand and passed througha screen so that the materials has an appropriate range of the particlesize distribution.

The amount of the culture fluid to be added to the raw ceramic materialare preferably in the range of 25 to 40% by weight.

The culture fluid and the ceramic material and, if necessary, a binderas well as a variety of additives are added simultaneously or in anappropriate sequence, and blended satisfactorily with an appropriatemixing means.

The blend thus obtained is next molded. The shape of the ceramicaccording to the present invention is not particularly limited and maybe made adapted to various applications described hereunder.

The blend thus molded is preferably dried and calcined.

Calcination temperature of the blend is preferably in the range of 700°to 1300° C., particularly 700° C. to 1050° C. The blend is preferablycalcined for 4 to 15 hours. After the calcination, the ceramic arecooled to give the functional ceramic according to the presentinvention.

Uses of ceramic

The ceramic according to the present invention have a wide variety ofbiological activities. Without intending to be bound by theory, it isbelieved that something derived from the microorganisms remains in theceramic and provides biological activities with ceramic even after thecalcination.

The ceramic according to the present invention has an activity ofimproving the soil. Therefore, according to another aspect of thepresent invention, there provides a composition for improving the soilcomprising the ceramic of the present invention as an active ingredient.There also provides a method for improving the soil comprising the stepof applying the ceramic of the present invention to the soil. Accordingto the preferred embodiment of the present invention, the ceramic whichis in the form of particles may apply the soil. The amount of theceramic applied is preferably in the range of 25 to 100 g per 1 m² ofthe soil.

Further, the ceramic according to the present invention has an activityof improving water quality or decomposing sewage or sludge, i.e., anaqueous solution. Therefore, according to a further aspect of thepresent invention, there provides a composition for improving waterquality or decomposing sewage or sludge comprising the ceramic of thepresent invention as an active ingredient. There also provides a methodfor improving water quality or decomposing sewage or sludge comprisingthe step of bringing the ceramic of the present invention into contactwith sewage or sludge. When used for improving water quality ordecomposing sewage or sludge, the ceramic of the present invention,preferably in the form of particles, may be spread over the bottom of acontainer in which waste water are contained or may be put in a bag andimmersed in the container. Alternatively, a fine powdery ceramic of thepresent invention may be coated on a surface of the container.

The ceramic of the present invention also has an activity of deodorizingan odor. Therefore, according to another aspect of the presentinvention, there provides a composition for deodorizing the odorcomprising the ceramic of the present invention as an active ingredient.There also provides a method for deodorizing the odor comprising thestep of bringing the ceramic of the present invention in contact withthe source of the odor. According to the preferred embodiment of thepresent invention, the amount of the ceramic used for the deodorizationis preferably in the range of 1 to 15 g/kg of the source of the odorsuch as garbage and wastes. Alternatively, it is also possible toprepare a bag having an activity of deodorizing the odor. The bag may beprepared by blending the powdery functional ceramic with papermanufacturing materials or plastic materials, preparing paper or plasticfilm with the paper materials or plastic materials, and preparing a bagmade of the paper or the plastic film thus obtained.

The ceramic of the present invention has an activity of improving fuels,such as gasoline. Therefore, according to another aspect of the presentinvention, there provides a composition for improving the fuelcomprising the ceramic of the present invention as an active ingredient.There also provides a method for improving the fuel comprising the stepof bringing the fuel into contact with the ceramic of the presentinvention.

The ceramic of the present invention has an activity of reducing harmfulcomponent levels in an exhaust gas. Therefore, according to a furtheraspect of the present invention, there provides a composition fortreating the exhaust gas to reduce harmful component levels in theexhaust gas, comprising the ceramic of the present invention as anactive ingredient. There also provides a method for cleaning up theexhaust gas comprising the step of bring the exhaust gas into contactwith the ceramic of the present invention. According to the preferredembodiment of the present invention, the ceramic of the presentinvention may be put in an exhaust pipe of a car or motorcycle.

The invention is illustrated in more detail by reference to thefollowing examples.

Example 1

Preparation of ceramic

Each of the culture fluids of Streptomyces albus (ATCC 3004),Streptoverticillium baldaccii (ATCC 23654), Nocardia asteroides (ATCC19247), Micromonospora chalcea (ATCC 12452), Rhodopseudomonassphaeroides (IFO 12203), Rhodospirillum rubrum (IFO 3986), Lactobacillusbulgaricus (IFO 3986), Propionibacterium freudenreichii (IFO 12391),Pediococcus halophilus (IFO 12172), Streptococcus lactis (IFO 12007),Streptococcus faecalis (IFO 3971), Aspergillus japonicus (IFO 4060),Aspergillus oryzae (IFO 4075), Mucor hiemalis (IFO 5303), Saccharomycescerevisiae (IFO 0304), Saccharomyces lactis (IFO 0433), Candida utilis(IF 0396) cultured in 4% molasses solution was prepared and blended inan amount of 20-35% by weight with Gaimome-clay. The blend wassufficiently kneaded, formed into particles. The particles were driedand calcined at 700° C. for 6 hours to give ceramic particles (particlediameter: 2-3 mm).

Comparative Example

Ceramic without fluid of microorganisms

Ceramic particles were prepared in the same manner as that of Example 1except that the culture fluid of the microorganism was not added.

Example 2

Improvement of soil

The particles of the ceramic obtained in Example 1 was applied in anamount of 50 g per 1 m² of the soil. Then, spinach, SANTOSAI (agreenstuff), and chiboul were cultured. Results are shown in Table 1.Culture in the soil with the ceramic of the present invention broughtabout the increased harvest in 10 to 20% or more as compared with theharvest in the soil without the ceramic.

                  TABLE 1                                                         ______________________________________                                        Effect of functional ceramic on harvests of vegetables                               Treated Area  Non-treated Area                                                  Height   Harvest/m.sup.2                                                                          Height Harvest/m.sup.2                           Product  (cm)     (kg)       (cm)   (kg)                                      ______________________________________                                        Spinach  35       4.5        33     3.8                                       SANTOSAI 32       4.6        30     4.0                                       Chiboul  45       5.4        43     4.6                                       ______________________________________                                    

Example 3

Water Quality Improvement (1)

The ceramic particles obtained in Example 1 were spread with a thicknessof about 1 cm over the bottom of a 50 liter container in which wastewater (BOD, 280 ppm; SS, 120 ppm) was contained. The change in the waterquality of the waste water was observed. Also, the change in the waterquality was observed in the case that the ceramic obtained inComparative Example were spread. The results are shown in Table 2.

                  TABLE 2                                                         ______________________________________                                        Water quality improvement                                                                     After                                                                      Before   1      3    5    7    9                                 Ceramic      treatment                                                                              day    days days days days                              ______________________________________                                        Example 1                                                                              BOD     280       50   20   5    3    3                                       SS      120       50   10   4    4    2                              Comparative                                                                            BOD     280      230  200  183  151  140                             Example  SS      120      110   98   81   64   60                             ______________________________________                                         BOD: Biological Oxygen Demand (ppm),                                          SS: Suspended Substance (ppm).                                           

Example 4

Water quality improvement (2)

The ceramic particles obtained in Example 1 were processed in the formof powder. A concrete bath which was not cured was prepared. The powderwas coated on the surface of the bath. And then, the bath was cured. Theconcrete bath was filled with waste water. Changes in water quality wasobserved. The results are shown in Table 3.

                  TABLE 3                                                         ______________________________________                                        Purification of water                                                                         After                                                                      Before   1      3    5    7    9                                 Ceramic      treatment                                                                              day    days days days days                              ______________________________________                                        Example 1                                                                              BOD          50     43   21   13    6                                         SS           10      7    5    3    2                                Comparative                                                                            BOD          50     48   45   44   41                                Example  SS           10      9    9    8    7                                ______________________________________                                         BOD: Biological Oxygen Demand (ppm),                                          SS: Suspended Substance (ppm).                                           

Example 5

Water Quality Improvement (3)

The ceramic particles obtained in Example 1 were charged as a filter ina filtering apparatus having a capacity of 300 liter/hour. Waste waterused in Example 3 was introduced into the filtering apparatus. Thechange in the quality of the filtrate was observed.

Filtration was conducted in the same manner as the above with theceramic obtained in Comparative Example to observe the change in thequality of filtrate.

The results are shown in Table 4.

                  TABLE 4                                                         ______________________________________                                        Purification of water                                                                     Before After                                                      Ceramic       treatment                                                                              2 hours 4 hours 6 hours                                ______________________________________                                        Example 1 BOD     280      5     1       0.01                                           SS      120      0.5   0       0                                    Comparative                                                                             BOD     280      140   100     51                                   Example   SS      120      25    21      18                                   ______________________________________                                         BOD: Biological Oxygen Demand (ppm),                                          SS: Suspensed Substance (ppm).                                           

Example 6

Deodorization (1)

The ceramic particles obtained in Example 1 or Comparative Example wasapplied in an amount of 3 g to 1kg of garbage from households. Thegarbage was sealed and left to stand for 10 days. Then, concentrationsof ammonia and hydrogen sulfide as the sources of unpleasant odor weremeasured. The results are shown in Table 5.

                  TABLE 5                                                         ______________________________________                                        Deodorization (1)                                                                                Hydrogen  Methyl- Trimethyl-                                        Ammonia   sulfide   mercaptan                                                                             amine                                    Ceramic  (ppm)     (ppm)     (ppm)   (ppm)                                    ______________________________________                                        Example 1                                                                              N.D.      N.D.      N.D.    N.D.                                     Comparative                                                                            4.4       2.81      0.051   0.131                                    Example                                                                       ______________________________________                                         N.D.: Nondetected.                                                       

Example 7

Deodorization (2)

The ceramic particles obtained in Example 1 were processed into powderand blended into paper manufacturing materials. Then, a paper bag wasprepared from the paper manufacturing material. The paper bag was filledwith garbage from households, sealed and left to stand for 10 days.Then, concentrations of the sources of the unpleasant odor such asammonia or hydrogen sulfide were measured.

The results are shown in Table 6.

                  TABLE 6                                                         ______________________________________                                        Deodorization (2)                                                                                Hydrogen  Methyl- Trimethyl-                                        Ammonia   sulfide   mercaptan                                                                             amine                                    Ceramic  (ppm)     (ppm)     (ppm)   (ppm)                                    ______________________________________                                        Example 1                                                                              N.D.      N.D.      N.D.    N.D.                                     Comparative                                                                            4.1       2.9       0.041   0.121                                    Example                                                                       ______________________________________                                         N.D.: Nondetected.                                                       

Example 8

Deodorization (3)

The ceramic particles obtained in Example 1 or Comparative Example wereprocessed into powder and blended in an amount of 10% into nylonmaterial. Then, a nylon bag was prepared from the nylon material. Thebag was filled with garbage from a households, sealed and left to standfor 10 days. Then, concentrations of the sources of the unpleasant odorsuch as ammonia or hydrogen sulfide were measured.

The results are shown in Table 7.

                  TABLE 7                                                         ______________________________________                                        Deodorization                                                                                    Hydrogen  Methyl- Trimethyl-                                        Ammonia   sulfide   mercaptan                                                                             amine                                    Ceramic  (ppm)     (ppm)     (ppm)   (ppm)                                    ______________________________________                                        Example 1                                                                              N.D.      N.D.      N.D.    N.D.                                     Comparative                                                                            4.4       3.3       0.045   0.135                                    Example                                                                       ______________________________________                                         N.D.: Nondetected.                                                       

Example 9

Decomposition of sludge

The ceramic particles obtained in Example 1 were mixed with sludgecollected from the bottom of the sea. The amount of the ceramic wasabout 100 g into 5 liters of the sludge. The mixture was left to standin a 10 liter clear glass bottle for days. Then, the amount of sludgeleft in the bottle was measured.

                  TABLE 8                                                         ______________________________________                                                     Initial 30 days   60 days                                                                             90 days                                  Ceramic      (liter) (liter)   (liter)                                                                             (liter)                                  ______________________________________                                        Example 1    5       4.5       3.9   3.0                                      Comparative  5       4.9       4.9   4.9                                      Example                                                                       ______________________________________                                    

Example 10

Improving fuel

The ceramic particles obtained in Example 1 or Comparative Example werecharged as a filter in a filtering apparatus having a capacity of 300liter/hour. A commercially available gasoline was circulated through thefiltering apparatus for hours. The gasoline obtained was then suppliedto a car to measure the travelling distance per fuel consumption.

The results are shown in Table 9.

                  TABLE 9                                                         ______________________________________                                                        Trial                                                         Ceramic           1st      2nd      3rd                                       ______________________________________                                        Example 1                                                                              Travelling dis-                                                                            331.2 km 328 km 334 km                                           tance per 40 litter                                                           Fuel expenses                                                                              8.28 km/l                                                                              8.2 km/l                                                                             8.35 km/l                               Comparative                                                                            Travelling dis-                                                                            228 km   288 km 288 km                                  Example  tance per 40 litter                                                           Fuel expenses                                                                              7.2 km/l 7.2 km/l                                                                             7.2 km/l                                ______________________________________                                    

Example 11

Reduction of harmful component levels in exhaust gas

A cylindrical pipe (diameter: 10-20 mm) of the ceramic of the presentinvention was prepare by substantially the same manner as thatExample 1. The ceramic pipe thus obtained was put in an exhaust pipe ofa car. The CO and HC levels in an exhaust gas was measured.

The results are shown in Table 10.

                  TABLE 10                                                        ______________________________________                                        Ceramic        CO (%)    HC (ppm)                                             ______________________________________                                        Example 1      0.02      0.1                                                  Comparative    0.4       1.3                                                  Example                                                                       ______________________________________                                    

What is claimed is:
 1. A process for preparing a ceramic comprisingcalcining a ceramic material with 25 to 40 weight percent ofmicroorganismsand/or culture fluid thereof at a temperature and for atime sufficient for calcination to take place, wherein at least fivemicroorganisms are selected and at least one microorganism is selectedfrom each of the five groups of actinomycetes, phototrophic bacteria,lactic acid bacteria, mold fungi and yeast whereinsaid actinomycetesbelong to genus Streptomyces, Streptoverticillium, Nocardia,Micromonospora, or Rhodococcus; said phototrophic bacteria belong togenus Rhodopseudomonas, Rhodospirillum, Chromatium, or Chlorobium; saidlactic acid bacteria belong to genus Lactobacillus, Propionibacterium,or Pediococcus; said mold fungi belong to genus Aspergillus or Mucor;and said yeast belong to genus Saccharomyces or Candida.
 2. A processaccording to claim 1, wherein one or more microorganisms ofactinomycetes are selected from the microorganisms which belong toStreptomyces albus, Streptoverticillium baldaccii, Nocardia asteroides,Micromonospora chalcea or Rhodococcus rhodochrous; one or moremicroorganisms of phototrophic bacteria are selected from themicroorganisms which belong to Rhodopseudomonas spheroids,Rhodospirillum rubrum, or Chlorobium limicola;one or more microorganismsof lactic acid bacteria are selected from the microorganisms whichbelong to Lactobacillus bulgaricus, Propionibacterium freudenreichii,Pediococcus halophilous, Streptococcus lactis or Streptococcus faecalis;one or more microorganisms of mold fungi are selected from themicroorganisms that belong to Aspergillus japonicus, Aspergillus oryzae,or Mucor hiemalis; and one or more microorganisms of yeast are selectedfrom the microorganisms which belong to Saccharomyces cerevisiae,Saccharomyces lactis or Candida utilis.
 3. A process according to claim1, wherein the ceramic material is selected from the group consisting ofclay, zeolite and bakuhan-seki.
 4. A process according to claim 1,wherein calcination is conducted at a temperature of 700° to 1300° C. 5.A process according to claim 1, wherein calcination is conducted for 4to 15 hours.